Potato water use and yield under furrow irrigation

Field experiments were conducted to study the effects of plant-furrow treatments and levels of irrigation on potato (Solanum tuberosum L.) water use, yield, and water-use efficiency. The experiments were carried out under deficit irrigation conditions in a sandy loam soil of eastern India in the winter seasons of 1991/92, 1992/93, and 1993/94. Two plant-furrow treatments and two levels of irrigation were considered. The two plant-furrow treatments were F₁ - furrows with single row of planting in each ridge with 45 cm distance between adjacent ridges, and F₂ - furrows with double rows of planting spaced 30 cm apart in each ridge with 60 cm distance between adjacent ridges. The two levels of irrigation (LOI) were I₁ - 0.9 IW/CPE and I₂ - 1.2 IW/CPE, where IW is irrigation water of 5 cm and CPE is cumulative pan evaporation. Treatment F₂ produced highest tuber yield in all years with average value of 10,610 kg ha ^-1 and 12,780 kg ha ^-1 at LOI of I₁ and I₂, respectively. On average, six irrigations with a total of 25 cm, and seven irrigations with a total of 30 cm were required for both treatments F₁ and F₂ at LOI of I₁ and I₂, respectively. Treatment F₂ resulted in a significantly higher number of branches and tubers per plant, foliage coverage and water-use efficiency for both irrigation levels than treatment F₁. Average daily crop evapotranspiration was found to range from 1.1 to 3.4 mm and from 1.2 to 3.9 mm for treatment F₁ and from 1.1 to 3.6 mm and from 1.2 to 4.0 mm for treatment F₂ at LOI of I₁ and I₂, respectively.     

Responses of grain sorghum to variable water supply under two irrigation frequencies

Summary Two experiments were conducted with Sorghum bicolor (L.) Moench Cv. Pioneer 846 in a deep loam soil in the 1977 season. Experiment I consisted of two line-source sprinkler plots, one irrigated at two-day intervals (HF) and the other every 10 to 14 days (NF). In comparable treatments of both regimes, the seasonal amount of water applied was the same. Since the subsoil was very dry at planting, the different amounts of water applied led to the development of a range of water stresses from none to severe. Experiment II was conducted in an adjacent area with a fully wetted soil profile. The treatments were irrigated every week (I) and nonirrigated (NI). Applied water was measured after each irrigation. Soil water content, leaf water potential, leaf-area index, ground cover and dry-matter accumulation were measured at frequent intervals, and yields were taken at the end of the growing season. Linear relations were found between both total dry-matter production and grain yield and seasonal evapotranspiration (ET) in both HF and NF regimes. With seasonal values of ET near the potential, grain yield and dry-matter production did not differ between irrigation frequencies. At low seasonal ET values, however, the NF regime gave greater yields of dry-matter and grain than did the HF regime.     

灌水量对烤烟产量和水分利用效率的影响

灌水时期不当或灌水量过大会降低烟叶的产量,同时造成水分的浪费,探究烟草适宜的灌水量至关重要。在蒸渗仪中开展试验,研究了不同灌水量对土壤水分、烤烟的水分利用效率和产量的影响。结果表明：烤烟 K326各处理不同土层含水率变化规律比较一致,（0,10]cm 土层含水率受气温、日照等气候因素较大;（10,20]cm 土壤含水率变化较剧烈;（20,60]cm 土壤含水率在整个生育期变化比较平缓,尤其在成熟后期各处理均出现不同程度的回升趋势,结合烤烟成熟期生理活动减弱、需水量减少,说明成熟期采取较小的灌水量比较适宜。成熟期烤烟的干物质产量在一定范围内随灌水量的增大而增加,如果继续加大灌水量将出现“报酬递减”现象。结合烟叶产量、烟株长势、耗水量和水分利用效率的结果,表明2700～3000 m3／hm2可以作为烤烟K326适宜的灌水量。在烤烟生产中,应均衡协调产量、水分利用效率与耗水量之间的关系,在高产前提下,适当减少灌水量,可达到既高产又节水的协调统一。     

Evapotranspiration, seed yield and water use efficiency of drip irrigated sunflower under full and deficit irrigation conditions

Deficit irrigation occurrence while maintaining acceptable yield represents a useful trait for sunflower production wherever irrigation water is limited. A 2-year experiment (2003–2004) was conducted at Tal Amara Research Station in the Bekaa Valley of Lebanon to investigate sunflower response to deficit irrigation. In the plots, irrigation was held at early flowering (stage F1), at mid flowering (stage F3.2) and at early seed formation (stage M0) until physiological maturity. Deficit-irrigated treatments were referred to as WS1, WS2 and WS3, respectively, and were compared to a well-irrigated control (C). Reference evapotranspiration (ET_rye-grass) and crop evapotranspiration (ET_crop) were measured each in a set of two drainage lysimeters of 2 m × 2 m × 1 m size cultivated with rye grass (Lolium perenne) and sunflower (Helianthus annuus L., cv. Arena). Crop coefficients (K_c) in the different crop growth stages were derived as the ratio (ET_crop/ET_rye-grass).

Lysimeter measured crop evapotranspiration (ET_crop) totaled 765 mm in 2003 and 882 mm in 2004 for total irrigation periods of 139 and 131 days, respectively. Daily ET_crop achieved a peak value of 13.0 mm day⁻¹ at flowering time (stage F3.2; 80–90 days after sowing) when LAI was >6.0 m² m⁻². Then ET_crop declined to 6.0 mm day⁻¹ during seed maturity phase. Average K_c values varied from 0.3 at crop establishment (sowing to four-leaf stage), to 0.9 at late crop development (four-leaf stage to terminal bud), to >1.0 at flowering stage (terminal bud to inflorescence visible), then to values <1.0 at seed maturity phase (head pale to physiological maturity). Measured K_c values were close to those reported by the FAO.

Average across years, seed yield at dry basis on the well-irrigated treatment was 5.36 t ha⁻¹. Deficit irrigation at early (WS1) and mid (WS2) flowering stages reduced seed yield by 25% and 14% (P < 0.05), respectively, in comparison with the control. However, deficit irrigation at early seed formation was found to increase slightly seed yield in WS3 treatment (5.50 t ha⁻¹). We concluded that deficit irrigation at early seed formation (stage M0) increased the fraction of assimilate allocation to the head, compensating thus the lower number of seeds per m² through increased seed weight. In this experiment, while deficit irrigation did not result in any remarkable increase in harvest index (HI), water use efficiency (WUE) was found to vary significantly (P < 0.05) among treatments, where the highest (0.83 kg m⁻³) and the lowest (0.71 kg m⁻³) values were obtained from WS3 and WS1 treatments, respectively. Finally, results indicate that irrigation limitation at early flowering (stage F1) and mid flowering (stage F3.2) should be avoided while it can be acceptable at seed formation (stage M0).     

滴灌水氮耦合对水氮利用及冬小麦产量的影响

以华北地区冬小麦为试验对象,参考直径20 cm标准蒸发皿的累计水面蒸发量E,通过2 a的大田试验(2012—2013),研究了大田地表滴灌条件下水氮耦合制度对作物耗水量、作物生理指标、产量、氮残留及水氮利用效率的影响,结果表明,冬小麦生育期内的耗水量、叶面积指数及产量受灌水定额的影响更为显著(P<0.05);滴灌条件下,当施氮量在120~290 kg/hm²时,水氮耦合效应对冬小麦耗水量的影响不具有统计学意义;在滴灌灌水定额为0.80E,施氮量为140~190 kg/hm²的水氮耦合模式下,冬小麦的产量较高,土壤硝态氮的当季残留较少,且进一步显著增加灌水定额和氮肥投入量将导致产量的明显下降;综合考虑冬小麦水氮利用效率和对地下水的潜在淋失风险,华北典型区滴灌水氮耦合的优化组合范围宜为灌水定额为0.80E,施氮量为140~190 kg/hm².     

Cotton yield and water use efficiency at various levels of water and N through drip irrigation under two methods of planting

The present investigation was undertaken to evaluate the effect of various levels of water and N application through drip irrigation on seed cotton yield and water use efficiency (WUE). In this experiment three levels of water (Epan 0.4, 0.3, and 0.2) and three levels of N (100, 75, and 50% of recommended N, 75 kg/ha) through drip were compared with check-basin method of irrigation under two methods of planting (normal sowing, NS; paired sowing, PS). The results revealed that when the same quantity of irrigation water and N was applied through drip irrigation system, it increased the seed cotton yield to 2144 from 1624 kg/ha (an increase of 32%) under check-basin method of irrigation. When the quantity of water through drip was reduced to 75%, the increase in seed cotton yield was 12%; however, when water was reduced to 50%, it resulted 2% lower yield than check-basin. The decrease in N through fertigation resulted in reduction in seed cotton yield at all the levels of water supply, but the magnitude of reduction was the highest at highest level of water supply. In paired sowing (PS), 20% higher seed cotton yield was obtained as compared with check-basin method under NS along with 50% saving of water. In paired sowing the sacrifice of 9% seed cotton yield as compared with NS resulted in saving of 50% water as well as the cost of laterals because there was one lateral for two paired rows. The WUE increased by 26% (22.1 from 17.6 kg/ha cm) in drip irrigation system when same quantity of water and N fertilizer was applied as compared with check-basin. WUE was not affected with quantity of water but decrease in rate of N caused a decrease in WUE at all the quantities of water applied. In general, WUE was higher in PS as compared with NS. The agronomic efficiency of nitrogen increased from 21.65 to 28.59 kg of seed cotton per kg of N applied when same quantity of water and N was applied through drip irrigation as compared with check-basin. However, decrease in quantity of water applied resulted in a decrease in agronomic efficiency of N but reverse was true for rates of N applied. When the same quantity of water and N was applied under both the methods of planting, PS produced 22% higher seed cotton yield and along with reduced cost owing to half the number of laterals required.     

Sorghum yield,water use and canopy temperatures under different levels of irrigation

This research was initiated to examine water use of differentially irrigated sorghum (Sorghum bicolor (L.) Moench) and to evaluate the plant water stress using canopy temperature measurements.Field experiments were conducted for 3 years characterised by different weather conditions at Montpellier, France. The crop was subjected to 14 differentially irrigated treatments which included, each year, a full irrigated and a dry treatment. Plant and soil measurements monitored during the crop cycle included soil water content, leaf water potential, and canopy temperature.Mid-day measurement of crop canopy temperature (Tc) /air temperature (Ta) difference reached a maximum of 7°C in the dry treatment and was maintained close to 0°C in full irrigated treatment. The relationships between (Tc-Ta) and vapour pressure deficit (VPD) commonly referred to as ‘baseline’ in the determination of crop water stress indicator (CWSI) were examined on function of wind speed and global solar radiation. Three approaches of estimating CWSI were compared. Summations of stress-degree-day (SDD) and temperature-stress-day (TSD) were well related to both relative evapotranspiration and yield (r² > 0.70).     

Evaluation of the influence of irrigation methods and water quality on sugar beet yield and water use efficiency

Rapid urbanization and industrialization have increased the pressure on limited existing fresh water to meet the growing needs for food production. Two immediate responses to this challenge are the efficient use of irrigation technology and the use of alternative sources of water. Drip irrigation methods may play an important role in efficient use of water but there is still limited information on their use on sugar beet crops in arid countries such as Iran. An experiment was conducted to evaluate the effects of irrigation method and water quality on sugar beet yield, percentage of sugar content and irrigation water use efficiency (IWUE). The irrigation methods investigated were subsurface drip, surface drip and furrow irrigation. The two waters used were treated municipal effluent (EC = 1.52 dS m⁻¹) and fresh water (EC = 0.509 dS m⁻¹). The experiments used a split plot design and were undertaken over two consecutive growing seasons in Southern Iran. Statistical testing indicated that the irrigation method and water quality had a significant effect (at the 1% level) on sugar beet root yield, sugar yield, and IWUE. The highest root yield (79.7 Mg ha⁻¹) was obtained using surface drip irrigation and effluent and the lowest root yield (41.4 Mg ha⁻¹) was obtained using furrow irrigation and fresh water. The highest IWUE in root yield production (9 kg m⁻³) was obtained using surface drip irrigation with effluent and the lowest value (3.8 kg m⁻³) was obtained using furrow irrigation with fresh water. The highest IWUE of 1.26 kg m⁻³ for sugar was obtained using surface drip irrigation. The corresponding efficiency using effluent was 1.14 kg m⁻³. Irrigation with effluent led to an increase in the net sugar yield due to an increase in the sugar beet root yield. However, there was a slight reduction in the percentage sugar content in the plants. This study also showed that soil water and root depth monitoring can be used in irrigation scheduling to avoid water stress. Such monitoring techniques can also save considerable volumes of irrigation water and can increase yield.     

Effect of irrigation and nitrogen on yield,yield components and water use efficiency of barley in Saudi Arabia

Water use efficiency and yield of barley were determined in a field experiment using different irrigation waters with and without nitrogen fertilizer on a sandy to loamy sand soil during 1994–1995 and 1995–1996. Depending upon different fertilizer treatments, the overall mean crop yield ranges for two crop seasons were: greenmatter from 19.48–55.0 Mg ha⁻¹ (well water) and 21.92–66.5 Mg ha⁻¹ (aquaculture effluent); drymatter from 6.86–20.69 Mg ha⁻¹ (well water) and 7.87–20.90 Mg ha⁻¹ (aquaculture effluent); biomass from 4.12–21.31 Mg ha⁻¹ (well water) and 8.10–19.94 Mg ha⁻¹ (aquaculture effluent) and grain yield from 2.12–5.50 Mg ha⁻¹ (well water) and 3.25–7.25 Mg ha⁻¹ (aquaculture effluent). The WUE for grain yield was 3.37–8.74 kg ha⁻¹ mm⁻¹ (well water) and 5.17–11.53 kg ha⁻¹ mm⁻¹ (aquaculture effluent). The WUE for total biomass ranged between 6.55–33.88 kg⁻¹ ha⁻¹ mm⁻¹ (well water) and 12.88–31.70 kg ha⁻¹ mm⁻¹ (aquaculture effluent). The WUE for drymatter was 10.91–32.90 kg ha⁻¹ mm⁻¹ (well water) and 12.51–33.22 kg ha⁻¹ mm⁻¹ (aquaculture effluent). It was found that grain yield and WUE obtained in T-4 and T-5 irrigated with well water and receiving 75 and 100% nitrogen requirements were comparable with T-4 and T-5 irrigated with aquaculture effluent and receiving 0 and 25% nitrogen requirements. In conclusion, application of 100 to 150 kg N ha⁻¹ for well water and up to 50 kg N ha⁻¹ for aquaculture effluent irrigation containing 40 Mg N l⁻¹ would be sufficient to obtain optimum grain yield and higher WUE of barley in Saudi Arabia.     

喷灌水肥与种植密度互作对水氮利用效率和冬小麦产量的影响

为研究豫北地区喷灌水肥一体化条件下不同种植密度和施氮频次对土壤水分、硝态氮含量及冬小麦产量的影响,开展田间试验.试验设置了2个种植密度(D1:187 kg/hm²、D2:262 kg/hm²)和3个施氮频次(F1:返青后追肥1次、F2:返青后追肥2次、F3:返青后追肥3次).试验结果表明:种植密度和施氮频次均显著影响冬小麦籽粒产量, 且两者间存在明显的互作效应.种植密度增大,冬小麦生育期0~100 cm土层土壤贮水量显著提高.主要生育期的根系生长层土壤含水量显著增加,其中孕穗期在100 cm土层深度的含水量D2较D1分别提高29.42%,3.10%和32.04%,灌浆期在80 cm土层深度的含水量D2较D1分别提高29.69%,27.52%和25.71%.当种植密度为262 kg/hm²,施氮频次为1次时,冬小麦产量较高,深层土层的土壤硝态氮当季残留较少.综合分析表明,该种植密度和施氮频次为当地冬小麦生育期的最优措施.     

Effect of timing of first and last irrigation on the yield and water use efficiency in cotton

With increasing concern about declining water resources, there is increasing thrust in improving water management in farming systems to improve water use efficiency. The present investigation was undertaken to determine the optimum timing for the first and last irrigation of cotton on the basis of meteorological approach for scheduling irrigations. The experiment was conducted in a split plot design with three timings of first irrigation as main-plots and three timing of last irrigation as sub-plots. Delay of first irrigation from 28 days after sowing (DAS) to 42 DAS, irrespective of last irrigation, resulted in an increase of 8, 14 and 17% in seed cotton yield during first, second and third year, respectively. The corresponding increases due to delay in the last irrigation from 130 to 170 DAS were 14, 32 and 8%, respectively. On the basis of 3 years average, application of first and last irrigation at optimum time (after 42 and 170 days after sowing) resulted in an increase of 36% in seed cotton yield without involving any additional cost. Water expense efficiency (WEE) increased by 54%.     

Cotton yield and applied water relationships under drip irrigation

Different irrigation scheduling methods and amounts of water ranging from deficit to excessive amounts were used in cotton (Gossypium hirsutum L.) irrigation studies from 1988 to 1999, at Lubbock, TX. Irrigation scheduling treatments based on canopy temperature (T_c) were emphasized in each year. Surface drip irrigation and recommended production practices for the area were used. The objective was to use the 12-year database to estimate the effect of irrigation and growing season temperature on cotton yield. Yields in the irrigation studies were then compared with those for the northwest Texas production region. An irrigation input of 58 cm or total water application of 74 cm was estimated to produce maximum lint yield. Sources of the total water supply for the maximum yielding treatments for each year averaged 74% from irrigation and 26% from rain. Lint yield response to irrigation up to the point of maximum yield was approximated as 11.4 kg ha⁻¹ cm⁻¹ of irrigation between the limits of 5 and 54 cm with lint yields ranging from 855 to 1630 kg ha⁻¹. The intra-year maximum lint yield treatments were not limited by water input, and their inter-year range of 300 kg ha⁻¹ was not correlated with the quantity of irrigation. The maximum lint yields were linearly related to monthly and seasonal heat units (HU) with significant regressions for July (P=0.15), August (P=0.07), and from May to September (P=0.01). The fluctuation of maximum yearly lint yields and the response to HU in the irrigation studies were similar to the average yields in the surrounding production region. The rate of lint yield increase with HU was slightly higher in the irrigation studies than in the surrounding production area and was attributed to minimal water stress. Managing irrigation based on real-time measurements of T_c produced maximum cotton yields without applying excessive irrigation.     

不同水量交替灌溉对木薯产量和水分利用的影响

为探讨作物旱后复水的补偿效应,采用不同水量交替灌溉方式研究木薯的生长、产量及水分利用效率的变化规律,设计了5种水分处理模式,分别为3种常规灌水处理(T1,T2和T3处理的灌水定额分别为10,20,30 mm)和2种交替灌水处理(T4处理:即对灌水定额10和20 mm进行轮回交替;T5处理:即对灌水定额10和30 mm进行轮回交替).结果表明:与T2处理相比,T5处理的总叶面积、总干物质质量、产量和水分利用效率分别显著增加31.1%,20.3%,64.6%和114.0%.与T3处理相比,T5处理节水33.3%,其总干物质质量下降较小,而根系干物质质量、水分利用效率和产量分别显著增加11.2%,119.0%和13.3%.因此,T5处理是有利于木薯产量和水分利用效率提高的最佳灌溉模式.     

Different drip irrigation regimes affect cotton yield, water use efficiency and fiber quality in western Turkey

Decreasing in water availability for cotton production has forced researchers to focus on increasing water use efficiency by improving either new drought-tolerant cotton varieties or water management. A field trial was conducted to observe the effects of different drip irrigation regimes on water use efficiencies (WUE) and fiber quality parameters produced from N-84 cotton variety in the Aegean region of Turkey during 2004 and 2005. Treatments were designated as full irrigation (T₁₀₀, which received 100% of the soil water depletion) and those that received 75, 50 and 25% of the amount received by treatment T₁₀₀ on the same day (treatments T₇₅; T₅₀ and T₂₅, respectively). The average seasonal water use values ranged from 265 to 753 mm and the average seed cotton yield varied from 2550 to 5760 kg ha⁻¹. Largest average cotton yield was obtained from the full irrigation treatment (T₁₀₀). WUE ranged from 0.77 kg m⁻³ in the T₁₀₀ to 0.98 kg m⁻³ in the T₂₅ in 2004 growing season and ranged from 0.76 kg m⁻³ in the T₁₀₀ to 0.94 kg m⁻³ in the T₂₅ in 2005 growing season. The largest irrigation water use efficiency (IWUE) was observed in the T₂₅ (1.46 kg m⁻³), and the smallest IWUE was in the T₁₀₀ treatment (0.81 kg m⁻³) in the experimental years. A yield response factor (k_y) value of 0.78 was determined based on averages of two years. Leaf area index (LAI) and dry matter yields (DM) increased with increasing water use for treatments. Fiber qualities were influenced by drip irrigation levels in both years. The results revealed that well-irrigated treatments (T₁₀₀) could be used for the semi-arid climatic conditions under no water shortage. Moreover, the results also demonstrated that irrigation of cotton with drip irrigation method at 75% level (T₇₅) had significant benefits in terms of saved irrigation water and large WUE indicating a definitive advantage of deficit irrigation under limited water supply conditions. In an economic viewpoint, 25.0% saving in irrigation water (T₇₅) resulted in 34.0% reduction in the net income. However, the net income of the T₁₀₀ treatment is found to be reasonable in areas with no water shortage.     

Effect of soil matric potential on tomato yield and water use under drip irrigation condition

Field experiment was carried out to investigate the effect of soil matric potential (SMP) on tomato yield, evapotranspiration (ET), water use efficiency (WUE) and irrigation water use efficiency (IWUE) under drip irrigation condition in North China Plain. The experiment included five treatments, which controlled SMP at 0.2 m depth immediately under drip emitter higher than −10 (S1), −20 (S2), −30 (S3), −40 (S4) and −50 kPa (S5), respectively, after tomato plant establishment. The results showed that different SMP affected irrigation amount and tomato ET. Irrigation amount decreased from 185 mm (S1) to 83.6 mm (S5) in 2004, and from 165 mm (S1) to 109 mm (S5) in 2005, respectively. The ET decreased from 270 mm (S1) to 202 mm (S5) in both years. However, it was found that SMP did not affect the tomato yield significantly, for the range of SMP investigated. Both WUE and IWUE increased as SMP decreased. The maximum WUE (253 and 217 kg/ha mm) and IWUE (620 and 406 kg/ha mm) were for S5 in 2 years, whereas the minimum WUE (178 and 155 kg/ha mm) and IWUE 261 and 259 kg/ha mm) were for S1 in 2004 and 2005. Based on the above results, therefore, it is recommended that if the tomatoes are well irrigated (SMP is higher than −20 kPa) during establishment, controlling SMP higher than −50 kPa at 0.2 m depth immediately under drip emitter can be used as an indicator for drip irrigation scheduling during following period of tomato growth in North China Plain.     

Improving water use efficiency in rice irrigation through wet-seeding

Since the early-1960's, when modern rice production technologies became available, more than 90% of the total irrigation water developed in south and southeast Asia is used for rice culture. But currently rice culture is highly inefficient in water use. As fresh water availability for agriculuture is becoming increasingly scarce, greater efficiency of water use in rice culture is deemed essential. Past experience indicates that effective implementation of water-efficient irrigation methods in rice farms within public sector irrigation systems is restricted by the difficulty of controlling water deliveries and distribution, and establishing a water charge system based on the actual amount of water used by farmers. Clearly, a rice production method that is inherently less water-requiring, or more water-efficient, would have an advantage over the traditional method in this respect. Recent studies conducted in the Philippines indicate that wet-seeded rice culture is superior to the traditional transplanted rice culture in terms of water efficiency. Other advantages of wet-seeded rice culture include its greater drought tolerance, less labor requirement for crop establishment and weed control, and higher returns from rice farming. This paper presents a comparative study of wet-seeded and transplanted rice cultures focusing on these aspects.     

分根区交替灌溉下水分亏缺对夏玉米生长和水分利用效率的影响

为探讨玉米节水灌溉方式的理论依据,通过桶栽试验研究了分根区交替灌溉(APRI)方式下,不同生育期水分亏缺对夏玉米生长、干物质累积质量、籽粒产量、总耗水量和水分利用效率(WUE)的影响.结果表明:常规灌溉(CI)方式下,苗期和全生育期水分亏缺的株高、叶面积和总耗水量均显著低于充分灌溉,但苗期水分亏缺可以提高WUE.相同的灌水方式和亏缺时期,中度亏缺的根干物质质量、地上和总干物质质量以及籽粒产量均显著高于重度亏缺;相同的灌水方式和灌水水平,苗期水分亏缺的株高、叶面积、根干物质质量、地上和总干物质质量以及总耗水量均显著的低于灌浆期,但籽粒产量和WUE均显著高于灌浆期;相同的灌水水平和亏缺时期,APRI的根干物质质量和总耗水量均显著低于CI的,但APRI的籽粒产量和水分利用效率均显著高于CI的.本研究结果表明,APRI在苗期进行中度亏缺有利于营养生长的调控,并达到节水高产,提高WUE的目的.     

Sugarcane water use from shallow water tables: implications for improving irrigation water use efficiency

The resource potential of shallow water tables for cropping systems has been investigated using the Australian sugar industry as a case study. Literature concerning shallow water table contributions to sugarcane crops has been summarised, and an assessment of required irrigation for water tables to depths of 2 m investigated using the SWIMv2.1 soil water balance model for three different soils. The study was undertaken because water availability is a major limitation for sugarcane and other crop production systems in Australia and knowledge on how best to incorporate upflow from water tables in irrigation scheduling is limited. Our results showed that for the three soils studied (representing a range of permeabilities as defined by near-saturated hydraulic conductivities), no irrigation would be required for static water tables within 1 m of the soil surface. Irrigation requirements when static water tables exceeded 1 m depth were dependent on the soil type and rooting characteristics (root depth and density). Our results also show that the near-saturated hydraulic conductivities are a better indicator of the ability of water tables below 1 m to supply sufficient upflow as opposed to soil textural classifications. We conclude that there is potential for reductions in irrigation and hence improvements in irrigation water use efficiency in areas where shallow water tables are a low salinity risk: either fresh, or the local hydrology results in net recharge.     

Grain yield and water use efficiency of two types of winter wheat cultivars under different water regimes

To improve grain yields of winter wheat and water-use efficiency in the water-shortage region of the North China Plain (NCP), field experiments involving three irrigation levels and two types of winter-wheat cultivars (Shijiazhuang 8 and Xifeng 20, with moderate and strongly drought tolerance, respectively) were conducted over three growing seasons with different levels of precipitation. The results showed that irrigation significantly improved the grain yield of both wheat cultivars. The response of grain yield was largest in the dry year, followed by the normal and wet years. Shijiazhuang 8 responded more strongly than Xifeng 20. Compared to aboveground biomass under no irrigation treatment, the aboveground biomass of Shijiazhuang 8 and Xifeng 20 improved by 87.0% and 57.8%, respectively, in a dry year, by 27.2% and 18.3%, respectively, in a normal year, and by 13.7% and 11.7%, respectively, in a humid year when irrigation were applied twice. The total water use (TWU) of the two cultivars also increased upon irrigation. The increase was more pronounced in the dry year than in the normal or humid years. However, there were no significant differences in the TWUs of the two cultivars. The water-use efficiency at grain-yield level (WUE_y) of Shijiazhuang 8 increased significantly upon irrigation in the dry year, did not change in the normal year, and showed a clear decline in the humid year, while the WUE_y of Xifeng 20 was reduced by irrigation in each of the three growing seasons. The harvest index (HI) was not altered by irrigation but it did vary by growing season. The HI of Shijiazhuang 8 was always higher than that of Xifeng 20. A positive correlation was found between both the WUE_y and the water-use efficiency at the aboveground-biomass level (WUE_bm) and the HI. This suggests that the changes in WUE_y as a result of irrigation are mainly due to changes in the WUE_bm and that the differences in WUE_y between the two cultivars were due to differences in WUE_bm and HI. These results suggest the following. (1) The TWUs in the two cultivars were roughly equal, although their levels of drought tolerance differed. (2) A wheat cultivar with moderate drought tolerance is expected to be more suitable for the semi-arid region of the NCP. The variety with strongly drought tolerance was able to keep its biomass high and to maintain grain yield under serious drought stress. (3) In order to both increase grain yield and WUE_y, two irrigations in a dry year, one irrigation in a normal year, and no irrigation in a humid year will give optimal results in the studied region.     

Effects of arrangement of surge-rootirrigation emitters on growth,yield andwater use efficiency of apple trees

Six-year old apple trees were selected for field experiment. The objective of this study was to obtain the reasonable arrangement of surge-root irrigation emitters in apple orchards. There were three factors: the buried depth H( 25,40,55 cm),the horizontal distance L( 30,40,60 cm) between the emitters and the trunk of the experimental tree,and the number of the irrigation emitters N( 1,2,4). The effect of the arrangement of surge-root irrigation emitters on the growth,yield and irrigation water use efficiency( IWUE) of apple trees were studied in Northern Shaanxi where the irrigation quota takes 60%-75% of the field water capacity. The results showed that the arrangement of emitters for surge-root irrigation had a significant effect on apple tree yield and IWUE,especially,the yield and IWUE reached 28 388. 17 kg/hm2 and 16. 83 kg/m3 in treatment T3,respectively. At the same L and N levels( T1,T2,and T3),the yield and IWUE in treatment T3 were the highest,and the yields in treatments T1 and T2 were decreased by 26.22% and 31.48%,while IWUE is reduced by14.02% and 18.12% compared with T3,respectively. At the same H and N levels( T3,T4,and T5),the yield and IWUE of apple trees were decreased with increasing L level. Especially,when L was 30 cm( T3),the yield and IWUE were the highest. The same L and H levels( T3,T6,and T7) could promote the growth of apple trees when N was 2( T3). Compared with treatment T3,it was found that the increment of new shoots was decreased by 8.07%-18.71%,and the fruit diameter was decreased by 5.41%-9.11%. Therefore,two emitters should be arranged symmetrically on both sides of an apple tree,each was buried at a 40 cm depth and 30 cm away from the trunk of the tree to effectively improve the yield and IWUE of the apple tree in mountainous areas in Northern Shaanxi.